'72 Chrysler 70 horse=Can't get lower unit off

I have a 1972 Chrysler 70 horse outboard model 707HE and can't get the lower unit off. I removed the six bolts (3 on each side of housing), The bolt at the rear of the trim tab, and I removed the pin from the shift shaft midway up the motor. The lower unit will not drop down. Possible shaft sized at the coupler? If so, how do I unseize the shaft?

Re: '72 Chrysler 70 horse=Can't get lower unit off

Some of those 2 piece lower units (the ones where the rear of the lower unit drops almost vertically to the cavitation plate) had a 12 point 5/16 bolt about 5 inches long going through the exhaust snout and up into the midleg. Removing that is normally the last bolt that holds the lower unit on. However, some ( the ones that have a long taper to the cavitation plate) have a short bolt holding the rear of the exhaust snout and after removing the snout, up inside would be another bolt--either 1/2 inch head or 5/16 allen head capscrew or, if the threads were stripped, a 3/8, 9/16 head bolt. This bolt must be removed to drop the lower unit.

If the shaft IS seized into the crankshaft, Chrysler recommended loosening the lower unit, loosening the block and starting the engine. While the engine is running, pry on the back of the block to tilt it and the rust should break free.

I never did it and it sounds dangerous--not to mention difficult since the block is normally stuck to the midleg, and all the shrouding must be removed to access the block studs. I would consider this method ONLY as a last resort.

By the way, the straight dropped lower units will bolt up the the tapered leg and vice-versa. However, the tapered lower unit is superior since the gearcase bolts to the upper portion with three bolts versus two for the older style. A two bolt gearcase will bolt to the three bolt upper portion however, the center bolt hole must be sealed in this application.

Re: '72 Chrysler 70 horse=Can't get lower unit off

Thanks for the information. I think the driveshaft is seized up top. I can pivot the lower unit about 30 degrees and look into the cavity. I didn't forget any bolts down there. Loosening and prying on the block with it running does seem scary but I may have to look into that or maybe turn the motor upside down so it can accept so penetrating oil. Thanks Again.